Inspection Procedure

NOTE: When replacing the skid control ECU, perform initialization of linear solenoid valve and calibration (see INITIALIZATION ).

CHECK HARNESS AND CONNECTOR (MOMENTARY INTERRUPTION)

Using the Techstream, check for any momentary interruption in the wire harness and connector corresponding to a DTC (see CHECK FOR INTERMITTENT PROBLEMS ).

ABS / VSC / TRAC:

SKID CONTROL ECU DIAGNOSTIC CHART

Tester Display	Measurement Item / Range	Normal Condition	Diagnostic Note
SPD SEN FR	FR speed sensor open detection / OPEN or NORMAL	NORMAL: Normal condition	-
SPD SEN FL	FL speed sensor open detection / OPEN or NORMAL	NORMAL: Normal condition	-

OK: There are no momentary interruptions.

HINT:

Perform the above inspection before removing the sensor and connector.

NG: Go to step 5

OK: Go to Next Step

READ VALUE OF TECHSTREAM (FRONT SPEED SENSOR)

Check the DATA LIST for proper functioning of the front speed sensor,

ABS / VSC / TRAC:

SKID CONTROL ECU DIAGNOSTIC CHART

Tester Display	Measurement Item / Range	Normal Condition	Diagnostic Note
WHEEL SPD FR	Wheel speed sensor (FR) reading / Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Actual wheel speed	Similar speed as indicated on speedometer
WHEEL SPD FL	Wheel speed sensor (FL) reading / Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Actual wheel speed	Similar speed as indicated on speedometer

OK: There is almost no difference from the displayed speed value.

HINT:

There is tolerance of+-10% in the speedometer indication.

NG: Go to step 4

OK: Go to Next Step

CHECK SPEED SENSOR AND SENSOR ROTOR SERRATIONS
1. Connect the oscilloscope to terminal FR+ and FR-, or FL+ and FL- of the skid control ECU.
2. Drive the vehicle at approximately 30 km/h (19 mph), and check the signal waveform.
  OK: A waveform as shown should be output.
  
  HINT:
  - As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the fluctuation in the output voltage becomes greater.
  - When noise is identified in the waveform on the oscilloscope, error signals are generated due to the speed sensor rotor's scratches, looseness or foreign matter deposited on it.
    
    Fig 1: Checking Signal Waveform
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: Go to step 6

OK: REPLACE SKID CONTROL ECU

INSPECT FRONT SPEED SENSOR

Disconnect the speed sensor connector.

Measure the resistance of the sensors.

Standard resistance:

for LH

STANDARD RESISTANCE REFERENCE CHART

Tester Connection	Specified Condition
A3-2 (FL+) - A3-1 (FL-)	1.4 to 1.8 kΩ
A3-1 (FL-) - Body ground	10 kΩ or higher
A3-2 (FL+) - Body ground	10 kΩ or higher

Fig 2: Inspecting Front Speed Sensor

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

for RH

STANDARD RESISTANCE REFERENCE CHART

Tester Connection	Specified Condition
A4-2 (FR+) - A4-1 (FR-)	1.4 to 1.8 kΩ
A4-1 (FR-) - Body ground	10 kΩ or higher
A4-2 (FR+) - Body ground	10 kΩ or higher

NOTE: Check the speed sensor signal after replacement (see TEST MODE PROCEDURE ).

NG: REPLACE FRONT SPEED SENSOR

OK: Go to Next Step

CHECK WIRE HARNESS (SKID CONTROL ECU - FRONT SPEED SENSOR)

Disconnect the S7 and S10 ECU connectors.
Disconnect the A3 and A4 sensor connectors,

Measure the resistance of the wire harness side connectors.

Standard resistance:

for LH

STANDARD RESISTANCE REFERENCE CHART

Tester Connection	Specified Condition
A3-1 (FL-) - S10-22(FL-)	Below 1 Ω
A3-2(FL+) - S10-28(FL+)	Below 1 Ω
A3-2 (FL+) - Body ground	10 kΩ or higher
A3-1 (FL-) - Body ground	10 kΩ or higher

for RH

STANDARD RESISTANCE REFERENCE CHART

Tester Connection	Specified Condition
A4-1 (FR-) - S7-22 (FR-)	Below 1 Ω
A4-2 (FR+) - S7-32 (FR+)	Below 1 O
A4-2 (FR+) - Body ground	10 kΩ or higher
A4-1 (FR-) - Body ground	10 kΩ or higher

Fig 3: Disconnecting S7 And S10 ECU Connectors

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to Next Step

CHECK SPEED SENSOR AND SENSOR ROTOR SERRATIONS
1. Connect the oscilloscope to terminals FR+ and FR-, or FL+ and FL- of the skid control ECU.
2. Drive the vehicle at approximately 30 km/h (19 mph), and check the signal waveform.
  OK: A waveform as shown should be output.
  
  HINT:
  - As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the fluctuation in the output voltage becomes greater.
  - When noise is identified in the waveform on the oscilloscope, error signals are generated due to the speed sensor rotor's scratches, looseness or foreign matter deposited on it.
NG: Go to step 7

Fig 4: Checking Signal Waveform
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: REPLACE SKID CONTROL ECU
INSPECT FRONT SPEED SENSOR INSTALLATION
1. Check the speed sensor installation.
  OK: The installation bolt is tightened properly and there is no clearance between the sensor and front steering knuckle.
  
  Torque: 8.0 N*m (82 kgf*cm, 71 in.*lbf)
  
  NOTE: Check the speed sensor signal after the replacement (see TEST MODE PROCEDURE ).
NG: REPLACE FRONT SPEED SENSOR

Fig 5: Checking Speed Sensor Installation
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: REPLACE SKID CONTROL ECU